Translating HTML5 canvas

JavascriptWeb DevelopmentFront End Scripts

Use the translate() method to translate canvas. HTML5 canvas provides a translate(x, y) method which is used to move the canvas and its origin to a different point in the grid.

Here argument x is the amount the canvas is moved to the left or right, and y is the amount it's moved up or down

Example

<!DOCTYPE HTML>
<html>
   <head>
      <style>
         #test {
            width:100px;
            height:100px;
            margin:0px auto;
         }
      </style>
     
      <script>
         function drawShape(){
            // get the canvas element using the DOM
            var canvas = document.getElementById('mycanvas');
           
            // Make sure we don't execute when canvas isn't supported
            if (canvas.getContext){
               // use getContext to use the canvas for drawing
               var ctx = canvas.getContext('2d');
               ctx.fillRect(0,0,300,300);
               for (i = 0; i < 3; i++) {
                  for (j = 0; j < 3; j++) {
                     ctx.save();
                     ctx.strokeStyle = "#FF0066";
                     ctx.translate(50+j*100,50+i*100);
                     drawSpirograph(ctx,10*(j+3)/(j+2),-2*(i+3)/(i+1),10);
                     ctx.restore();
                  }
               }
            } else {
              alert('You need Safari or Firefox 1.5+ to see this demo.');
            }
         }
         
         function drawSpirograph(ctx,R,r,O){
            var x1 = R-O;
            var y1 = 0;
            var i = 1;
            ctx.beginPath();
            ctx.moveTo(x1,y1);
            do {
            if (i>20000) break;
            var x2 = (R+r)*Math.cos(i*Math.PI/72) - (r+O)*Math.cos(((R+r)/r)*(i*Math.PI/72));
            var y2 = (R+r)*Math.sin(i*Math.PI/72) - (r+O)*Math.sin(((R+r)/r)*(i*Math.PI/72));
            ctx.lineTo(x2,y2);
            x1 = x2;
            y1 = y2;
            i++;
            } while (x2 != R-O && y2 != 0 );
            ctx.stroke();
         }
      </script>
   </head>

   <body id = "test" onload = "drawShape();">
      <canvas id = "mycanvas" width = "400" height = "400"></canvas>
   </body>
</html>
raja
Published on 06-Apr-2018 08:02:09
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